HDAC9 and hepatocellular carcinoma: The combination of HDAC inhibitor such as vorinostat (SAHA) and rhamnetin (an inhibitor of SIRT1) with the antineoplastic drugs could overcome the drug resistance (especially sorafenib resistance) in HCC and notably augmented the anticancer responses (Lachenmayer et al., 2012; Yuan et al., 2014; Li et al., 2021; Wang et al., 2021).